Date of Award


Degree Type


Degree Name

Master of Engineering Science


Electrical and Computer Engineering


Dr. Gerry Moschopoulos


It is standard practice to use two separate power converters to convert an ac input voltage to a desired and isolated dc output voltage. A front-end ac-dc converter is used to convert the input ac voltage into an intermediate dc voltage which is then fed into a dc-dc converter with transformer isolation. The front-end converter also performs input power factor correction (PFC) to shape the input currents to be sinusoidal and in phase with the input voltages to maximize the use of the available source power.

Conventional two-stage power conversion, however, requires two power con­ verters and there has been considerable interest to try to integrate the PFC and dc-dc conversion functions in a single power converter to reduce cost and complexity. Although many of these single-stage converters have been proposed for low power, single-phase applications, there have been relatively few higher power three-phase converters that have been proposed. This is due to the challenges faced when trying to perform PFC and dc-dc conversion for a wider load range.

A new three-phase, single-stage ac-dc full-bridge converter is proposed in this thesis. The outstanding features of the new converter are that it is relatively simple and it can perform PFC using standard phase-shift pulse width modulation (PWM). In the thesis, derivation of the converter is discussed and its general operation is re­ viewed. The modes of operation of the converter are explained in detail and analyzed and the results of the analysis are used to develop guidelines for its design. The feasibility of the proposed converter is confirmed with experimental results that were obtained from a prototype and are presented in this thesis.



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